The year must be between 1769 and this year.
The price and mileage must not be negative.
[x] Don't put invalid values in db. Fixed in: 3ae33562d78c38d41a8f01dd7faad1b0ee20eadc
[ ] Show an error to the user. Tried to fix it in: f9de01e28fffc124cdc76c9a32ea0164accf7033. Abandoned as of issue: 3786ddd00b3091c5ed5a58f68e8ba116883f9eb9. Causes a lot of problems, mostly because of the new block editor.
The year must be between 1769 and this year. The price and mileage must not be negative.
Worked on in: https://github.com/DevriX/tues-interns-2020/tree/feature-cars-validation